The transfer of information between nerve cells occurs when chemicals called neurotransmitters are released into the synapse, the junction between neurons. Electrical impulses in the neuron cause tiny vesicles (graphic) loaded with neurotransmitters to be released into the synapse.

Today's Nature reports on a new technique that researchers have created to image the movement of individual vesicles after they have released their neurotransmitter cargo. The new technique helps answer questions like the rate at which synaptic vesicles are recycled which helps illuminate how much information nerve cells can transmit.

There are three distinct ways that a "used vesicle" can be recycled from the surface of the nerve cell once it has released its cargo:

• "Kiss-and-Run" mode is the fastest, less than a second
  
• “Compensatory” mode is slower, up to 21 seconds
  
• “Stranded” mode leaves the vesicle stuck at the surface until the next nerve impulse triggers its retrieval

"The optical recording technique devised by Stevens and Gandhi involves genetically modifying a gene for one type of vesicle protein to incorporate a special form of green fluorescent protein. This modified fluorescent protein, developed by other researchers, does not fluoresce under acidic conditions normally present in vesicles fully loaded with neurotransmitter. However, when the vesicle releases its payload, the interior becomes less acidic and the vesicle glows a bright green."